Thursday, January 7, 2016

On Tonight’s Episode: “Fatty” Microbes!

By HJInterviewer: (To the audience) Maybe you’ve heard before that water makes up
about 98% of the total molecules in the human body. You might be skeptical; we
aren’t splashing around on the floor after all. OK, the number may seem a bit
misleading since water molecules are a lot smaller than the other molecules being
compared, such as proteins. But still, even if we go by the weight of the
molecules, water dominates at about 65% (1). What if I told you that some organisms dedicate
that much of its weight for fats? No, I’m not talking about obesity. I’m
talking about microscopic organisms that can mass-produce fats when the right
time comes. Here with me today are Lipomyces
starkeyi, Yarrowia lipolytica,
and Chlorella vulgaris. (To the
microbes) Thanks for joining me, guys!

Starkey:
In a way, yes. We start storing carbons once we run out of nitrogen (2–4). As you may or may not know, nitrogen is
essential—

Ella:
Because we need nitrogen in our DNA and proteins! It’s impossible for us to grow
and reproduce without additional nitrogen sources.

Rowie:
Yeah, so we start gathering all the carbons we can find and store them in the
form of fats. Fatty acids are mostly made of carbon and hydrogen, so you can
see why we choose to store carbons this way.

Starkey:
Then we chill and hope for better times to come. It’s basically what you humans
do; when you eat extra carbons, you store them as fats for future use.

Interviewer: (Looks down at himself and changes the subject) Ella, you mentioned
that you microbes are not able to reproduce under nitrogen-limiting conditions.
How do you feel about that?

Ella:
I mean… Sometimes life sets you back and you can’t do anything about it.
Obviously our dream is to become two cells—as François Jacob put it—but hey, at
least we’re still alive. Motherhood is still a possibility in the future.

Interviewer: (Turning to Rowie and Starkey) So what about you two? Can you tell
us a little bit about yourselves?

Starkey:
Well, I’m obviously not green like Ella, but I’m round and cute!

Rowie:
(Offended) Hey, being round isn’t the only way to be cute. I’m cute when I go
through my filamentous phase too (6)…

Interviewer: OK, moving on. I’m sure you’ve heard about the global energy and
environmental crises that we’re facing today. There is an effort to use clean
and renewable energies such as solar, geothermal, and wind energies. Another
example is biofuels, which are fuels derived from biomass. Biofuels used to be
made from corn or sugarcanes, but the industry faced backlash once the food
versus fuel controversy arose. Also, the sheer amount of resources used for
growing and converting the plants to biofuels caused the final product to be more
costly than its competitor, fossil fuels. Second generation biofuels was then established
to close this gap by using cheap, inedible—at least for humans—agricultural byproducts
and wastes (7). What are your thoughts on this?

Starkey:
Well, I know some humans are trying to use me to help convert biomass into
biofuels. I’m pretty good at eating sewage sludge (2), potato starch wastewater (8), monosodium glutamate (MSG) wastewater (9), and corn cob (10). By eating cheap food and making a lot of fats
that can be used for biofuel production—around 63% of my dry weight—my
lifestyle is applicable to second generation biofuels (2).

Rowie:
People are also trying to use me for biofuel applications (6). I originally make less fats than Starkey—around
15% dry weight—but some researchers have gotten my fat content up to almost 90%
through genetic engineering (3)!

Starkey:
That’s impressive. They haven’t gotten very far with me because they’re still trying
to figure out how to manipulate my DNA efficiently. As you may or may not know,
one DNA manipulation technique doesn’t work across all yeasts. Oftentimes what
works well in one species do not work well, if at all, in another. There have
been some success recently (11, 12), so we’ll see if these protocols work in other
labs and something useful comes out of it.

Ella:
Cool. Well, I can accumulate up to 53% of my weight as fats (4). But I’m extra special because I can make my own
food. All I need is some light, water, and carbon dioxide (CO2) from
the air. The light strikes the electrons donated by water, and when the
electrons give up its energy, I capture it for future use. With this energy, I
incorporate CO2 into small compounds to make bigger ones, like fats.
I will admit that I make more fats when I get to eat a prepared meal; making my
own food is a lot of work! So people have focused on feeding me wastewater to
produce fats to be used for biofuels (13, 14).

Interviewer: So do you guys think the biofuel industry will be successful?

Rowie:
I mean, we’ll see. If you humans can figure out a way to keep the costs lower
than fossil fuels, why not?

Ella:
But honestly, we could care less about the energy crisis you guys are dealing
with. We don’t drive cars or heat our homes, you know? I guess the only issue
is any negative impact that processes such as drilling and fracking have on the
environment.

Starkey:
Yeah, please keep us in mind when you guys are about to do something that’ll
hurt us and other organisms—directly and indirectly—on this planet! Believe it
or not, the Earth does NOT revolve around you humans.

No comments:

Post a Comment

About Us

This blog represents the work of students from one of the few courses devoted to Eukaryotic Microbiology as a whole. This is a new experiment for this course that we hope will be a successful fusion of student learning and science communication. Enjoy, but play nice, comments are welcome but mean-spirited comments will be deleted.